Free Electrons

Electrons Libres - Embedded Linux Experts

  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
/*
 *  Based on documentation provided by Dave Jones. Thanks!
 *
 *  Licensed under the terms of the GNU GPL License version 2.
 *
 *  BIG FAT DISCLAIMER: Work in progress code. Possibly *dangerous*
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/cpufreq.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/timex.h>
#include <linux/io.h>
#include <linux/delay.h>

#include <asm/cpu_device_id.h>
#include <asm/msr.h>
#include <asm/tsc.h>

#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
#include <linux/acpi.h>
#include <acpi/processor.h>
#endif

#define EPS_BRAND_C7M	0
#define EPS_BRAND_C7	1
#define EPS_BRAND_EDEN	2
#define EPS_BRAND_C3	3
#define EPS_BRAND_C7D	4

struct eps_cpu_data {
	u32 fsb;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
	u32 bios_limit;
#endif
	struct cpufreq_frequency_table freq_table[];
};

static struct eps_cpu_data *eps_cpu[NR_CPUS];

/* Module parameters */
static int freq_failsafe_off;
static int voltage_failsafe_off;
static int set_max_voltage;

#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
static int ignore_acpi_limit;

static struct acpi_processor_performance *eps_acpi_cpu_perf;

/* Minimum necessary to get acpi_processor_get_bios_limit() working */
static int eps_acpi_init(void)
{
	eps_acpi_cpu_perf = kzalloc(sizeof(*eps_acpi_cpu_perf),
				      GFP_KERNEL);
	if (!eps_acpi_cpu_perf)
		return -ENOMEM;

	if (!zalloc_cpumask_var(&eps_acpi_cpu_perf->shared_cpu_map,
								GFP_KERNEL)) {
		kfree(eps_acpi_cpu_perf);
		eps_acpi_cpu_perf = NULL;
		return -ENOMEM;
	}

	if (acpi_processor_register_performance(eps_acpi_cpu_perf, 0)) {
		free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
		kfree(eps_acpi_cpu_perf);
		eps_acpi_cpu_perf = NULL;
		return -EIO;
	}
	return 0;
}

static int eps_acpi_exit(struct cpufreq_policy *policy)
{
	if (eps_acpi_cpu_perf) {
		acpi_processor_unregister_performance(0);
		free_cpumask_var(eps_acpi_cpu_perf->shared_cpu_map);
		kfree(eps_acpi_cpu_perf);
		eps_acpi_cpu_perf = NULL;
	}
	return 0;
}
#endif

static unsigned int eps_get(unsigned int cpu)
{
	struct eps_cpu_data *centaur;
	u32 lo, hi;

	if (cpu)
		return 0;
	centaur = eps_cpu[cpu];
	if (centaur == NULL)
		return 0;

	/* Return current frequency */
	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
	return centaur->fsb * ((lo >> 8) & 0xff);
}

static int eps_set_state(struct eps_cpu_data *centaur,
			 struct cpufreq_policy *policy,
			 u32 dest_state)
{
	u32 lo, hi;
	int i;

	/* Wait while CPU is busy */
	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
	i = 0;
	while (lo & ((1 << 16) | (1 << 17))) {
		udelay(16);
		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
		i++;
		if (unlikely(i > 64)) {
			return -ENODEV;
		}
	}
	/* Set new multiplier and voltage */
	wrmsr(MSR_IA32_PERF_CTL, dest_state & 0xffff, 0);
	/* Wait until transition end */
	i = 0;
	do {
		udelay(16);
		rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
		i++;
		if (unlikely(i > 64)) {
			return -ENODEV;
		}
	} while (lo & ((1 << 16) | (1 << 17)));

#ifdef DEBUG
	{
	u8 current_multiplier, current_voltage;

	/* Print voltage and multiplier */
	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
	current_voltage = lo & 0xff;
	pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
	current_multiplier = (lo >> 8) & 0xff;
	pr_info("Current multiplier = %d\n", current_multiplier);
	}
#endif
	return 0;
}

static int eps_target(struct cpufreq_policy *policy, unsigned int index)
{
	struct eps_cpu_data *centaur;
	unsigned int cpu = policy->cpu;
	unsigned int dest_state;
	int ret;

	if (unlikely(eps_cpu[cpu] == NULL))
		return -ENODEV;
	centaur = eps_cpu[cpu];

	/* Make frequency transition */
	dest_state = centaur->freq_table[index].driver_data & 0xffff;
	ret = eps_set_state(centaur, policy, dest_state);
	if (ret)
		pr_err("Timeout!\n");
	return ret;
}

static int eps_cpu_init(struct cpufreq_policy *policy)
{
	unsigned int i;
	u32 lo, hi;
	u64 val;
	u8 current_multiplier, current_voltage;
	u8 max_multiplier, max_voltage;
	u8 min_multiplier, min_voltage;
	u8 brand = 0;
	u32 fsb;
	struct eps_cpu_data *centaur;
	struct cpuinfo_x86 *c = &cpu_data(0);
	struct cpufreq_frequency_table *f_table;
	int k, step, voltage;
	int ret;
	int states;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
	unsigned int limit;
#endif

	if (policy->cpu != 0)
		return -ENODEV;

	/* Check brand */
	pr_info("Detected VIA ");

	switch (c->x86_model) {
	case 10:
		rdmsr(0x1153, lo, hi);
		brand = (((lo >> 2) ^ lo) >> 18) & 3;
		pr_cont("Model A ");
		break;
	case 13:
		rdmsr(0x1154, lo, hi);
		brand = (((lo >> 4) ^ (lo >> 2))) & 0x000000ff;
		pr_cont("Model D ");
		break;
	}

	switch (brand) {
	case EPS_BRAND_C7M:
		pr_cont("C7-M\n");
		break;
	case EPS_BRAND_C7:
		pr_cont("C7\n");
		break;
	case EPS_BRAND_EDEN:
		pr_cont("Eden\n");
		break;
	case EPS_BRAND_C7D:
		pr_cont("C7-D\n");
		break;
	case EPS_BRAND_C3:
		pr_cont("C3\n");
		return -ENODEV;
		break;
	}
	/* Enable Enhanced PowerSaver */
	rdmsrl(MSR_IA32_MISC_ENABLE, val);
	if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
		val |= MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP;
		wrmsrl(MSR_IA32_MISC_ENABLE, val);
		/* Can be locked at 0 */
		rdmsrl(MSR_IA32_MISC_ENABLE, val);
		if (!(val & MSR_IA32_MISC_ENABLE_ENHANCED_SPEEDSTEP)) {
			pr_info("Can't enable Enhanced PowerSaver\n");
			return -ENODEV;
		}
	}

	/* Print voltage and multiplier */
	rdmsr(MSR_IA32_PERF_STATUS, lo, hi);
	current_voltage = lo & 0xff;
	pr_info("Current voltage = %dmV\n", current_voltage * 16 + 700);
	current_multiplier = (lo >> 8) & 0xff;
	pr_info("Current multiplier = %d\n", current_multiplier);

	/* Print limits */
	max_voltage = hi & 0xff;
	pr_info("Highest voltage = %dmV\n", max_voltage * 16 + 700);
	max_multiplier = (hi >> 8) & 0xff;
	pr_info("Highest multiplier = %d\n", max_multiplier);
	min_voltage = (hi >> 16) & 0xff;
	pr_info("Lowest voltage = %dmV\n", min_voltage * 16 + 700);
	min_multiplier = (hi >> 24) & 0xff;
	pr_info("Lowest multiplier = %d\n", min_multiplier);

	/* Sanity checks */
	if (current_multiplier == 0 || max_multiplier == 0
	    || min_multiplier == 0)
		return -EINVAL;
	if (current_multiplier > max_multiplier
	    || max_multiplier <= min_multiplier)
		return -EINVAL;
	if (current_voltage > 0x1f || max_voltage > 0x1f)
		return -EINVAL;
	if (max_voltage < min_voltage
	    || current_voltage < min_voltage
	    || current_voltage > max_voltage)
		return -EINVAL;

	/* Check for systems using underclocked CPU */
	if (!freq_failsafe_off && max_multiplier != current_multiplier) {
		pr_info("Your processor is running at different frequency then its maximum. Aborting.\n");
		pr_info("You can use freq_failsafe_off option to disable this check.\n");
		return -EINVAL;
	}
	if (!voltage_failsafe_off && max_voltage != current_voltage) {
		pr_info("Your processor is running at different voltage then its maximum. Aborting.\n");
		pr_info("You can use voltage_failsafe_off option to disable this check.\n");
		return -EINVAL;
	}

	/* Calc FSB speed */
	fsb = cpu_khz / current_multiplier;

#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
	/* Check for ACPI processor speed limit */
	if (!ignore_acpi_limit && !eps_acpi_init()) {
		if (!acpi_processor_get_bios_limit(policy->cpu, &limit)) {
			pr_info("ACPI limit %u.%uGHz\n",
				limit/1000000,
				(limit%1000000)/10000);
			eps_acpi_exit(policy);
			/* Check if max_multiplier is in BIOS limits */
			if (limit && max_multiplier * fsb > limit) {
				pr_info("Aborting\n");
				return -EINVAL;
			}
		}
	}
#endif

	/* Allow user to set lower maximum voltage then that reported
	 * by processor */
	if (brand == EPS_BRAND_C7M && set_max_voltage) {
		u32 v;

		/* Change mV to something hardware can use */
		v = (set_max_voltage - 700) / 16;
		/* Check if voltage is within limits */
		if (v >= min_voltage && v <= max_voltage) {
			pr_info("Setting %dmV as maximum\n", v * 16 + 700);
			max_voltage = v;
		}
	}

	/* Calc number of p-states supported */
	if (brand == EPS_BRAND_C7M)
		states = max_multiplier - min_multiplier + 1;
	else
		states = 2;

	/* Allocate private data and frequency table for current cpu */
	centaur = kzalloc(sizeof(*centaur)
		    + (states + 1) * sizeof(struct cpufreq_frequency_table),
		    GFP_KERNEL);
	if (!centaur)
		return -ENOMEM;
	eps_cpu[0] = centaur;

	/* Copy basic values */
	centaur->fsb = fsb;
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
	centaur->bios_limit = limit;
#endif

	/* Fill frequency and MSR value table */
	f_table = &centaur->freq_table[0];
	if (brand != EPS_BRAND_C7M) {
		f_table[0].frequency = fsb * min_multiplier;
		f_table[0].driver_data = (min_multiplier << 8) | min_voltage;
		f_table[1].frequency = fsb * max_multiplier;
		f_table[1].driver_data = (max_multiplier << 8) | max_voltage;
		f_table[2].frequency = CPUFREQ_TABLE_END;
	} else {
		k = 0;
		step = ((max_voltage - min_voltage) * 256)
			/ (max_multiplier - min_multiplier);
		for (i = min_multiplier; i <= max_multiplier; i++) {
			voltage = (k * step) / 256 + min_voltage;
			f_table[k].frequency = fsb * i;
			f_table[k].driver_data = (i << 8) | voltage;
			k++;
		}
		f_table[k].frequency = CPUFREQ_TABLE_END;
	}

	policy->cpuinfo.transition_latency = 140000; /* 844mV -> 700mV in ns */

	ret = cpufreq_table_validate_and_show(policy, &centaur->freq_table[0]);
	if (ret) {
		kfree(centaur);
		return ret;
	}

	return 0;
}

static int eps_cpu_exit(struct cpufreq_policy *policy)
{
	unsigned int cpu = policy->cpu;

	/* Bye */
	kfree(eps_cpu[cpu]);
	eps_cpu[cpu] = NULL;
	return 0;
}

static struct cpufreq_driver eps_driver = {
	.verify		= cpufreq_generic_frequency_table_verify,
	.target_index	= eps_target,
	.init		= eps_cpu_init,
	.exit		= eps_cpu_exit,
	.get		= eps_get,
	.name		= "e_powersaver",
	.attr		= cpufreq_generic_attr,
};


/* This driver will work only on Centaur C7 processors with
 * Enhanced SpeedStep/PowerSaver registers */
static const struct x86_cpu_id eps_cpu_id[] = {
	{ X86_VENDOR_CENTAUR, 6, X86_MODEL_ANY, X86_FEATURE_EST },
	{}
};
MODULE_DEVICE_TABLE(x86cpu, eps_cpu_id);

static int __init eps_init(void)
{
	if (!x86_match_cpu(eps_cpu_id) || boot_cpu_data.x86_model < 10)
		return -ENODEV;
	if (cpufreq_register_driver(&eps_driver))
		return -EINVAL;
	return 0;
}

static void __exit eps_exit(void)
{
	cpufreq_unregister_driver(&eps_driver);
}

/* Allow user to overclock his machine or to change frequency to higher after
 * unloading module */
module_param(freq_failsafe_off, int, 0644);
MODULE_PARM_DESC(freq_failsafe_off, "Disable current vs max frequency check");
module_param(voltage_failsafe_off, int, 0644);
MODULE_PARM_DESC(voltage_failsafe_off, "Disable current vs max voltage check");
#if IS_ENABLED(CONFIG_ACPI_PROCESSOR)
module_param(ignore_acpi_limit, int, 0644);
MODULE_PARM_DESC(ignore_acpi_limit, "Don't check ACPI's processor speed limit");
#endif
module_param(set_max_voltage, int, 0644);
MODULE_PARM_DESC(set_max_voltage, "Set maximum CPU voltage (mV) C7-M only");

MODULE_AUTHOR("Rafal Bilski <rafalbilski@interia.pl>");
MODULE_DESCRIPTION("Enhanced PowerSaver driver for VIA C7 CPU's.");
MODULE_LICENSE("GPL");

module_init(eps_init);
module_exit(eps_exit);